1. Field of the Invention
The present invention relates to an improvement on a manual-wind camera provided with a wind lever which is manually operated to wind the film frame by frame.
2. Description of the Related Art
Manual-wind cameras having a film winding mechanism provided with a wind lever (i.e., thumb-operated lever) which is manually operated to wind the film frame by frame are known in the art.
Conventional cameras of such a type are provided with a pulse generator which generates pulses in accordance with the film winding via the operation of the wind lever. Pulses generated by the pulse generator are counted by a counter to release the engagement of the wind lever with the take-up spool at the moment the counted number of the counter becomes identical to a reference pulse number which corresponds to a predetermined appropriate film-winding amount, so that the film is wound by the appropriate film-winding amount each time the film is wound by one frame.
In conventional manual-wind cameras using a roll-film having no sprocket holes such as Brownie film (e.g., 120 or 220 format film), turning the wind lever slowly makes the film winding speed slow while turning the wind lever quickly makes the film winding speed fast. However, the amount of operation of the wind lever does not exactly correspond to the amount of winding of the film because the film slips on the film guide roller, the amount of rotation thereof corresponding to the number of pulses generated by the aforementioned pulse generator, especially when the film is wound at a fast speed, i.e., when the wind lever is turned quickly. Accordingly, the amount of winding of the film by one frame varies slightly depending on the film winding speed. Furthermore, if the film winding speed is fast, even if the engagement of the wind lever and the spool is released, until they are actually released, the film can wind faster than the low film wind speed, or due to momentum, the spool does not stop immediately and winds on a little further. Even if the spool is lock-engaged when the film has finished winding, so that the film is stopped from being wound, the film can wind faster than the low film wind speed and be wound substantially more than a predetermined amount until the spool has actually been lock-engaged. If the amount of winding of the film by one frame is excessive, one or more exposures of the roll-film may be lost (e.g., the last exposure on the film may be lost), resulting in a substantial financial loss since roll-film having no sprocket holes such as Brownie film is usually expensive as compared with conventional 35 mm film.